Patent Document 1 discloses the following technique. Specifically, two sets of combined conductors each including flat conductor wires each of which is continuously formed in a meandering (rectangular waves) pattern and which overlap one on the other with displacement are assembled in overlapping relation to form an overlapped conductor assembly. This assembly is wound in multiple turns to form a cage-shaped coil (“cage coil”). In this cage coil, core pieces of a split core divided from the outer periphery to the inner periphery are inserted. A shrink fit ring is fitted around the outer periphery of the split core to fasten the core as a stator core.
Patent Document 2, on the other hand, discloses a method of inserting a coil in slots of a stator core in such a manner that a conductor wire is wound to form a coil to be inserted in the slots, the coil is set on a cylindrical coil insertion jig, which is then placed inside the stator core, and the coil is inserted from the insertion jig into the slots.
Patent Document 3 discloses that a distributed winding coil with its leading end to be inserted is bent toward an axis.